outlineview: merge class method definitions helper contexts
If we don't merge all those context end up with a tree like this:
+-+- FooClass
| \-- method1() |
+-+- FooClass
| \-- method2() |
+-+- FooClass
| \-- method3() |
\ OtherStuff
Now we get the following structure instead:
+-+- FooClass
| +-- method1() |
| +-- method2() |
| \-- method3() |
\ OtherStuff